The invention pertains to a coated article wherein the coated article comprises a substrate and a coating scheme on the substrate. These coated articles are useful in wear-resistant applications such as, for example without limitation, metal cutting, metal forming and tribological applications to extend the useful life of wear parts. More specifically, the invention pertains to such a coated article wherein the coating scheme includes a PVD coating region. The PVD coating region comprises one or more coating layers applied by physical vapor deposition (PVD) techniques, and wherein at least one coating layer contains yttrium. The coating layer can have a thickness greater than about 100 nanometers, or the coating layer can be without limitation a nanolayer(s) wherein the thickness is less than or equal to about 100 nanometers. The PVD coating region has a high hardness so as to provide suitable wear properties.
Physical Vapor Deposition (PVD) processes (often just called thin film processes) are atomistic deposition processes in which material is vaporized from a solid source in the form of atoms, transported in the form of a vapor through a vacuum or low pressure gaseous (or plasma) environment to the substrate where it condenses. Typically, PVD processes are used to deposit films with thicknesses in the range of a few nanometers to thousands of nanometer; however they can also be used to form multilayer coatings, graded composition deposits, very thick deposits and freestanding structures. PVD processes can be used to deposit films of elements and alloys as well as compounds using reactive deposition processes. In reactive deposition processes, compounds are formed by the reaction of depositing material with the gas environment such as nitrogen (e.g. titanium nitride, TiN). See Donald M. Mattox, Handbook of Physical Vapor Deposition (PVD) Processing, Society of Vacuum Coaters, Albuquerque, N. Mex. (1998), pp. 3-4.
Commercial coated products that have a PVD hard coating layer thereon are known. Table 1 below sets forth the chemistry, hardness, and other properties.
TABLE 1Properties of Commercially KnownPVD Coatings on Coated Cutting InsertsCoatingHardnessYoung'sNameChemistryLayers(GPa)Modulus (GPa)TiNTiNsingle coating24.8551layerTiN/TiCNTiN/TiCNmultiple sets of30.1545multialternatingcoating layersof TiN andTiCNTiAlN(Ti55 at %single coating27.6552Al45 at %)NlayerTiN/AlTiN(Ti60 at %multiple sets of28.5541Al40 at %)Nalternatingcoating layersof TiN andAlTiNAlTiN(Ti37 at %single coating25.2359Al63 at %)NlayerAlCrN(Cr37 at %single coating29.4514Al63 at %)NlayerIn Table I, the chemistry of the overall coating scheme is set forth in atomic percent of the elements, except for nitrogen. The hardness and Young's Modulus are set forth in GPa (gigapascals) and were measured by a nanoindentation technique. Specifically, the hardness and Young's Modulus were obtained using the nanoindentation technique per ISO 14577-1 standard procedure with the indentation set at 0.25 microns.
In the context of metal cutting applications and all other things being equal, a coating layer with a higher hardness typically increases the useful tool life of the coated cutting insert, and a lower hardness typically decreases the useful tool life of the coated cutting insert. This correlation also appears to be true for metal forming and tribological applications (e.g., wear parts).
U.S. Pat. No. 6,033,768 to Muenz et al. pertains to a hard material for use with cutting tools, especially for use in the coolant-free and lubricant-free machining of metals like die steels or aluminum alloys. According to Muenz et al., yttrium is added in the range of 0.1 to 4.0 atomic percent, preferably in the range of 1.5 to 2.0 atomic percent to ternary TiAlN alloys or in the following multilayer coatings: TiAlN/CrN, TiAlN/ZrN, TiAlN/TiN, TiAlN/MoN, and TiAlN/WN. To achieve the goal, in Muenz et al. the yttrium must be unevenly distributed over the entire hard material layer in the growth direction of the coating. Using what Muenz et al. terms “preferred deposition conditions”, the nitride coating composition is 40 at % of titanium, 56 at % of aluminum, 2 at % of yttrium, and 2 at % of chromium.
PCT Published Patent Application WO 2009/110829 to Johansson et al. pertains to a coated cutting tool wherein the coating includes at least one cubic structured layer of (Ti1-(x+z)SiXMez)N wherein 0.04<x<0.20, and 0<z<0.10 wherein Me is one or more of Y, Hf, Nb, Ta, Mo, W, Mn, Fe and Zn, preferably Y, Nb, Mo and Fe. United States Published Patent Application No. US 2010/0129168 A1 to Waki et al. pertains to a coating layer that has a first layer and a second layer. The first layer comprises Ti1-a-b-c-dAlaWbSicMd(C1-xN) wherein M is at one selected from Nb, Mo, Ta, Hf and Y. The second layer comprises Ti1-e-f-g AleSifM′g(C1-xN) wherein M′ is at one selected from Nb, Mo, Ta, Hf and Y.
It would highly desirable to provide a coated article that has a hard coating that exhibits improved properties wherein the coated article is useful in wear-resistant applications such as, for example, metal cutting, metal forming, and tribological applications to extend the useful life of wear parts. It would be further highly desirable to provide such a coated article that has a hard coating applied by physical vapor deposition that exhibits such improved properties.
It would be still further highly desirable to provide such a coated article that has a PVD coating region that exhibits improved properties (e.g., a higher hardness) and wherein the PVD coating region contains aluminum and yttrium and nitrogen and at least one element selected from the group of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten and silicon. It would be still further highly desirable to provide such a coated article that has a PVD coating region that exhibits improved properties (e.g., a smaller grain size) and wherein the PVD coating region contains aluminum and yttrium and nitrogen and at least one element selected from the group of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten and silicon. It would be still further highly desirable to provide such a coated article that has a PVD coating region that exhibits improved properties and wherein the PVD coating region contains aluminum and yttrium and nitrogen and at least one element selected from the group of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten and silicon.